1. Field of the Invention
The present invention generally relates to a signal transmission and reception in a communication system, and more particularly to an apparatus and method for transmitting and receiving a signal in a Space Time Frequency Block Code (STFBC) scheme in a communication system based on a single carrier transmission.
2. Description of the Related Art
Recently, the transmit diversity technology has been proposed which can increase channel capacity and link reliability by spatially arranging multiple transmit antennas without increasing a bandwidth or transmission power. A Single Carrier-Frequency Domain Equalization (SC-FDE) scheme has been proposed which exploits Space Time Block Coding (STBC) for providing transmit diversity gain.
FIG. 1 illustrates a structure of the conventional STBC transmission sequence.
Referring to FIG. 1, STBC data is transmitted through two antennas 101 and 103. At this time, symbol blocks 110, 120, 130, and 140 are sequentially transmitted in a time domain. Cyclic Prefixes (CPs) 112, 122, 132, and 142, serving as guard intervals, are inserted between the symbol blocks 110, 120, 130, and 140. At this time, two symbol blocks, i.e., n-th blocks 110 and 130, to be transmitted through the two antennas 101 and 103, are to have the same channel state.
When the STBC scheme is applied to a single carrier transmission scheme, for example, an SC-FDE scheme, the same channel state is maintained between the symbol blocks in a slow fading environment, such that performance is guaranteed. There is a problem, however, in that the performance is not guaranteed in a fast fading environment.
Furthermore, a Space Frequency Block Coding (SFBC) scheme is more robust to the fading environment in comparison with the STBC scheme. However, because the SFBC scheme is a multi-carrier scheme for applying a block code to a neighbor subchannel or carrier, it cannot be directly applied to the single carrier transmission scheme, i.e., the SC-FDE scheme. Even though the SFBC scheme is applied to the single carrier transmission scheme, its performance is guaranteed in a frequency non-selective fading channel, but degrades in a frequency selective fading channel.
Thus, when channel characteristics of a communication system are fast fading channel and frequency selective fading channel, and specifically, when the STBC or SFBC scheme is applied to the single carrier transmission system, the overall system performance can be degraded in the channels with the above-described channel characteristics.